We have previously shown that certain alkylphosphocholine analogs are preferentially taken up and retained by malignant solid tumor (i.e., solid tumor cancer) cells. In U.S. Patent Publication No. 2014/0030187, which is incorporated by reference herein in its entirety, Weichert et al. disclose using analogs of the base compound 18-(p-iodophenyl)octadecyl phosphocholine (NM404; see FIG. 1) for detecting and locating, as well as for treating, a wide variety of solid tumor cancers. For example, if the iodo moiety is an imaging-optimized radionuclide, such as iodine-124 ([124I]-NM404), the analog can be used in positron emission tomography-computed tomography (PET/CT) or single-photon emission computed tomography (SPECT) imaging of adult solid tumors. Alternatively, if the iodo moiety is a radionuclide optimized for delivering therapeutic doses of radiation to the solid tumors cells in which the analog is taken up, such as iodine-125 or iodine-131 ([125I]-NM404 or [131I]-NM404), the analog can be used to treat solid tumors.
However, there are currently no long-lived computerized tomography (CT) or magnetic resonance (MR) imaging agents that have been shown to successfully target tumor cells in vivo. Non-specific short-lived agents in both modalities are used for cancer imaging by contrasting normal organ tissues while in the process of renal or hepatobiliary excretion. There are currently a variety of radiopharmaceuticals available for tumor imaging, but these are limited by non-specificity for malignancy, the inability to distinguish cancer from inflammation, short biological half-life, and generally poor spatial resolution associated with PET and SPECT scanning modalities.
Accordingly, there is a need in the art for a tumor-specific agent for use in MR scanning, CT scanning, or in both imaging methods. Such a tumor-specific agent for MR or CT scanning would represent at least a ten-fold improvement in the spatial resolution currently attainable with positron emission agents and PET scanning.